George Soros's philanthropy network sought to obscure its close coordination with a liberal Jewish advocacy group connected to the Obama administration and to campaigns designed to increase pressure on Israel and bolster the U.S.-Iranian relationship, newly leaked documents show.

Documents apparently taken from the servers of Soros's Open Society Foundations (OSF) and uploaded to the Internet by the self-described "hacktivist group" DC Leaks state that OSF "works closely" with J Street on issues like delivering resources to the Hamas-occupied Gaza Strip. But the docs emphasize that those ties must be downplayed.

"In order to reduce potential risks associated with OSI's affiliation with this initiative," the 2009 memorandum states, "limit coordination and strategic communication to supportive/understanding groups in D.C. such as J Street." OSI stands for Open Society Institute, part of Soros's Foundation network.

Non-public connections between Soros, a Hungarian-American billionaire, and J Street have repeatedly proven controversial.

Statements by J Street long suggested the group did not take funding from Soros. J Street founder Jeremy Ben-Ami joked in 2010 that his group "got tagged as having [Soros's] support, without the benefit of actually getting funded!" Months later, it was revealed that the Soros family secretly donated $750,000 to the group over several years. J Street then claimed that they had "always said that [they] would be very pleased to have funding from Mr. Soros."

The newly released documents shed light on this controversy, in which J Street acknowledged Soros's toxic reputation but quietly engaged him and his groups anyway—and then publicly expressed enthusiasm after it was revealed they had ongoing ties.

A senior official at a Washington, D.C. pro-Israel organization described the documents as bringing J Street into a secret campaign to damage Israel's security.

"The leaked documents outline a media and lobbying campaign designed to undermine the U.S.-Israel relationship by exploiting, among other things, toxic discourse linked to the anti-Jewish conspiracy theories of Walt and Mearsheimer," said the source.

"And here you have sections where they say that they work closely with J Street, which is supposed to be a pro-Israel Jewish group, and the documents say that coordination shouldn't become public knowledge because it would endanger J Street's reputation. No kidding."

Ben-Ami has since reiterated that he "made a mistake in not publicizing the decision by George Soros to start funding J Street after our launch."

Soros and his family remain "one of the largest" J Street donors as of 2014, with a yearly donation of $500,000.

J Street did not respond to requests for comment about the current status of its relationship with Soros, or its past or present obfuscation of that relationship.